U.S. patent number 8,135,328 [Application Number 12/051,457] was granted by the patent office on 2012-03-13 for cleaning blade.
This patent grant is currently assigned to Canon Kasei Kabushiki Kaisha. Invention is credited to Taku Hatanaka, Shoji Inoue, Kenichi Mochizuki.
United States Patent |
8,135,328 |
Mochizuki , et al. |
March 13, 2012 |
Cleaning blade
Abstract
A cleaning blade is provided which does not cause contamination
of other parts even when being stored for a long period of time in
a high temperature and high humidity environment. The cleaning
blade is set in an image forming apparatus employing an
electrostatic transfer process, including a blade member and a
support member to rub and remove residual toner remaining on a
photosensitive drum provided to the image forming apparatus, in
which the total amount of nitrogen-containing compounds extracted
with methanol from the cleaning blade is 12 .mu.g or less per cm of
the cleaning blade in its longitudinal direction.
Inventors: |
Mochizuki; Kenichi (Ushiku,
JP), Inoue; Shoji (Ushiku, JP), Hatanaka;
Taku (Moriya, JP) |
Assignee: |
Canon Kasei Kabushiki Kaisha
(Tsukuba-shi, JP)
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Family
ID: |
39872329 |
Appl.
No.: |
12/051,457 |
Filed: |
March 19, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080260440 A1 |
Oct 23, 2008 |
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Foreign Application Priority Data
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Apr 18, 2007 [JP] |
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2007-109126 |
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Current U.S.
Class: |
399/350;
521/94 |
Current CPC
Class: |
G03G
21/0017 (20130101) |
Current International
Class: |
G03G
21/00 (20060101); C08G 18/38 (20060101) |
Field of
Search: |
;399/350 ;528/82,422
;521/94-95 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Gray; David
Assistant Examiner: Lactaoen; Billy J
Attorney, Agent or Firm: Fizpatrick, Cella, Harper &
Scinto
Claims
What is claimed is:
1. A cleaning blade which is set in an image forming apparatus
employing an electrostatic transfer process, comprising a blade
member and a support member to rub and remove residual toner
remaining on a photosensitive drum provided to the image forming
apparatus, wherein the blade member comprises a urethane elastomer
containing an amino alcohol having an active hydrogen group, with
the amino alcohol having the active hydrogen group including at
least N,N-dimethylaminohexanol or
N,N,N'-trimethyl-2-hydroxyethylpropylenediamine, and wherein a
total amount of the amino alcohol having an active hydrogen group
extracted with methanol from 1 gram of the urethane elastomer
performed for four days in an environment of 25.degree. C. is 2.6
.mu.g or more and 50.0 .mu.g or less.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cleaning blade which is set in
an image forming apparatus employing an electrostatic transfer
process and which includes a blade member and a support member to
rub and remove residual toner remaining on a photosensitive drum
provided to the image forming apparatus.
The image forming apparatus employing an electrostatic transfer
process, such as an electrophotographic copying machine, a laser
beam printer and a facsimile, performs copying and printing by
adhering toner to an electrostatic latent image formed on a
photosensitive drum, and then transferring the toner image to
copying paper. As a method of removing residual toner remaining on
the photosensitive drum after transferring the toner image, a
method has been put into practical use, which employs a cleaning
blade having a blade member formed of urethane elastomer and a
support member (holder).
2. Description of the Related Art
Conventionally, as a material forming such a blade member, a
polyester urethane elastomer, particularly a thermosetting urethane
elastomer, has been used which is excellent in mechanical strength
such as abrasion resistance and is less likely to creep (permanent
deformation due to contact stress).
The above-mentioned polyester urethane elastomer is usually
produced by a prepolymer method, a semi one-shot method, a one-shot
method, etc., using polyisocyanate, polyol, a chain extender, and a
catalyst. In this production, a catalyst is added for shortening a
molding cycle and improving production efficiency of the blade
member. Conventionally, as such a catalyst, triethylenediamine
(TEDA), dimethylimidazole (DMI), etc., have been used. However, the
polyester urethane elastomer produced using the catalyst has such a
problem that the above-mentioned catalyst remaining inside is
vaporized by moisture in the air or heat, resulting in
contamination of other parts. Then, as a result of other parts
being contaminated by the above-mentioned catalyst, image defects
may occur.
As a means for solving the problem, a case has been introduced in
which a catalyst is used having 2 or 3 hydroxyl groups in a
molecule (e.g., see Japanese Patent Application Laid-Open No.
H07-290603). When a catalyst having such a feature is used, the
hydroxyl groups contained in a molecule react with isocyanate
contained in a prepolymer. Therefore, the catalyst can be prevented
from exuding out of urethane elastomer. However, even when the
catalyst has hydroxyl groups in a molecule, not all the hydroxyl
groups react with isocyanate in a prepolymer. In such a case, an
unreacted catalyst may be exuded out of urethane elastomer by
moisture in the air or heat.
Since image forming apparatuses are miniaturized and are improved
in image quality with the spread of an electrophotographic copying
machine or a laser beam printer, a positional relationship with
other parts becomes closer than before, or a space around a
cleaning blade decreases. Therefore, even when the amount of the
catalyst vaporized by moisture in the air or heat is small, other
parts are liable to be contaminated, which results in a condition
that image defects are likely to occur.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above-mentioned
present circumstances, and is aimed at providing a cleaning blade
which does not cause contamination of other parts even when the
cleaning blade is stored for a long period of time in a high
temperature and high humidity environment.
The present invention which has solved the above problem is a
cleaning blade which is set in an image forming apparatus employing
an electrostatic transfer process, including a blade member and a
support member to rub and remove residual toner remaining on a
photosensitive drum provided to the image forming apparatus, in
which the total amount of nitrogen-containing compounds extracted
with methanol from the cleaning blade is 12 .mu.g or less per cm of
the cleaning blade in its longitudinal direction.
Further features of the present invention will become apparent from
the following description of exemplary embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-sectional view illustrating an example
of an embodiment according to the present invention.
FIG. 2 is a schematic perspective view illustrating an example of
an embodiment according to the present invention.
FIG. 3 is a schematic perspective view illustrating an example of a
cutting position of a blade member to obtain a test sample
according to the present invention.
FIG. 4 is a schematic perspective view illustrating an example of a
methanol extraction method according to the present invention.
TABLE-US-00001 DESCRIPTION OF SIGNS 1: a support member 2: a blade
member 3: a test sample 4: methanol 5: a closed container
DESCRIPTION OF THE EMBODIMENTS
The present invention can provide a cleaning blade in which other
parts are not contaminated by an unreacted catalyst.
The cleaning blade of the present invention is set in an image
forming apparatus employing an electrostatic transfer process, and
includes a blade member a support member to rub and remove residual
toner remaining on a photosensitive drum provided to the image
forming apparatus. The cleaning blade has such a feature that the
total amount of nitrogen-containing compounds extracted with
methanol from the cleaning blade is 12 .mu.g or less per cm of the
cleaning blade in its longitudinal direction.
A method of producing the cleaning blade of the present invention
is not limited to some specific method, and it can be produced by
any known method. For example, the cleaning blade of the present
invention can be produced as follows. That is, a support member is
prepared, and an adhesive is applied to one end face of the support
member. Then, the support member with the adhesive is placed in,
for example, a cleaning blade molding die formed of an upper die
and a lower die. In this case, the support member is placed in the
molding die in a state that the one end face with the adhesive
applied thereto is projected into a cavity. Subsequently, a liquid
raw material composition containing polyisocyanate, polyol, a chain
extender, a urethane curing catalyst, etc., is injected into a
cavity of the cleaning blade molding die, and heated to be cured.
Subsequently, the cured material is released from the die, and cut
into a given size, thereby producing a cleaning blade in which the
blade member is formed on a holder member.
In the cleaning blade of the present invention, the total amount of
nitrogen-containing compounds extracted with methanol from the
cleaning blade is required to be 12 .mu.g or less per cm of the
cleaning blade in its longitudinal direction. When the total amount
of nitrogen-containing compounds extracted with methanol is larger
than 12 .mu.g per cm of the cleaning blade in its longitudinal
direction, other parts may be contaminated, which leads to the
occurrence of image defects. As other parts which are disposed near
the cleaning blade, for example, a photosensitive drum and a
charged roller are cited. The longitudinal direction of each of the
parts and the longitudinal direction of the cleaning blade are the
same. Thus, when other parts are contaminated by the cleaning
blade, the total amount of nitrogen-containing compounds which
exude per cm of the cleaning blade in its longitudinal direction
serves as an important index.
Moreover, when the blade member is formed of a urethane elastomer,
the total amount of nitrogen-containing compounds extracted from
the urethane elastomer with methanol is preferably equal to or
smaller than 50 .mu.g per g of the urethane elastomer. When the
total amount of nitrogen-containing compounds extracted with
methanol is adjusted to be equal to or smaller than 50 .mu.g per g
of the urethane elastomer, the above-mentioned contamination of
other parts can be prevented.
Thus, according to the cleaning blade of the present invention,
other parts are not contaminated, and hence, image defects do not
occur, because the total amount of nitrogen-containing compounds
which exude from the cleaning blade is adjusted to a suitable
value.
As for polyisocyanates which may be used in the present invention,
there is no specific limitation, but
4,4'-diphenylmethanediisocyanate (MDI) is preferred, and the
following polyisocyanates may be also used: for example, isophorone
diisocyanate, 4,4'-dicyclohexyl diisocyanate,
trimethylhexamethylene diisocyanate, tolylene diisocyanate,
carbodiimide-modified diisocyanate, polymethylenephenyl
polyisocyanate, o-toluidine diisocyanate, naphthalene diisocyanate,
xylylene diisocyanate, hexamethylene diisocyanate, p-phenylene
diisocyanate, lysine diisocyanate methyl ester. Those may be used
alone or in combination.
As for polyols which may be used in the present invention, there is
no specific limitation, and for example, conventionally known
polyols may be used. Specifically, the following may be cited:
adipate-type polyesterpolyols such as polyethyleneadipate
polyesterpolyol, polybutyleneadipate polyesterpolyol,
polyhexyleneadipate polyesterpolyol, polyethylene-propyleneadipate
polyesterpolyol, polyethylene-butyleneadipate polyesterpolyol, and
polyethylene-neopentyleneadipate polyesterpolyol. In addition,
polyesterpolyols such as a polycaprolactone-type polyesterpolyol
obtained by a ring opening polymerization of caprolactone,
polyethyleneglycol, polypropyleneglycol and polytetramethylene
glycol, may be cited. Polycarbonate diols may also be used. These
may be used alone or in combination.
As for chain extenders which may be used in the present invention,
there is no specific limitation, and for example, conventionally
known polyols may be used. Specifically, the following may be
cited: polyols each having a molecular weight of 200 or less, such
as 1,4-butanediol, ethyleneglycol, diethyleneglycol,
propyleneglycol, dipropyleneglycol, hexanediol,
1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, xylyleneglycol,
triethyleneglycol, trimethylolpropane, glycerine, pentaerythritol,
sorbitol and 1,2,6-hexanetriol. These may be used alone or in
combination.
As urethane curing catalysts usable in the present invention, amine
compounds such as tertiary amines, organometallic compounds, etc.,
may be cited. The urethane curing catalyst is roughly classified
into an isocyanuration catalyst and an urethanization catalyst. In
the present invention, it is preferable that an isocyanuration
catalyst and an urethanization catalyst are used in combination as
the urethane curing catalyst.
The isocyanuration catalyst usable in the present invention
includes tertiary amines such as N-ethylpiperidine,
N,N'-dimethylpiperazine, and N-ethyl morpholine; hydroxides or
organic weak acid salts of tetraalkylammonium such as
tetramethylammonium, tetraethylammonium, and tetrabutylammonium;
hydroxides or organic weak acid salts of hydroxyalkylammonium such
as trimethyl hydroxypropyl ammonium and triethyl hydroxypropyl
ammonium; alkaline metal salts of carboxylic acids such as acetic
acid, propionic acid, butyric acid, caproic acid, capric acid,
valeric acid, octylic acid, myristic acid, and naphthenic acid. Of
those, alkaline metal salts of carboxylic acids are preferable
which do not bring about blooming after molding so as not to exert
an influence on other parts. Those may be used alone or in
combination.
As the urethanization catalyst usable in the present invention,
commonly-used polyurethane curing catalysts may be cited. For
example, amine catalysts may be cited. To be specific, the
following can be mentioned: amino alcohols such as
dimethylethanolamine and N,N,N'-trimethyl-2-hydroxyethyl
propylenediamine; trialkylamines such as triethylamine; tetraalkyl
diamines such as N,N,N',N'-tetramethyl-1,3-butanediamine; cyclic
amines such as triethylenediamine,
1,8-diazabicyclo(5,4,0)undecene-7, and N-methyl morpholine; a
piperazine-type amine; a triazine-type amine; an imidazole-type
amine; etc. Moreover, metal catalysts, which are generally used for
urethane, may be used, and dibutyl tin dilaurate may be cited as an
example. Of those, the amino alcohol having in its molecule an
active hydrogen group for isocyanate is preferable, taking into
account its reactivity and the fact that it does not have an
influence on other parts after molding. N,N-dimethylhexanolamine
having high reactivity between an active hydrogen group in its
molecule and isocyanate is more preferable. Those may be used alone
or in combination.
As for a method of producing the cleaning blade of the present
invention, there is no specific limitation, and it may be suitably
selected from known methods. For example, the cleaning blade can be
produced as follows. First, a cleaning blade molding die is
prepared. Next, a chain extender containing a prepolymer for a
urethane elastomer in which a polyisocyanate and a polyester polyol
are partially polymerized and a catalyst is put in a casting
machine, and then mixed and stirred at a given ratio in a mixing
chamber, thereby obtaining a liquid mixture. The liquid mixture is
put in the molding die, and then, reacted and cured. Subsequently,
the cured material is released from the die, and cut into a given
size, thereby producing a cleaning blade.
Next, the present invention will be described in detail with
reference to examples. The present invention is by no means limited
to these examples.
The following raw materials were used in examples.
(1) 4,4-diphenylmethane diisocyanate (MILLIONATE MT (trade name)
manufactured by NIPPON POLYURETHANE INDUSTRY CO., LTD)
(2) Polybutyleneadipate (NIPPORAN4010 (trade name) manufactured by
NIPPON POLYURETHANE INDUSTRY CO., LTD)
(3) Polyhexyleneadipate (NIPPORAN164 (trade name) manufactured by
NIPPON POLYURETHANE INDUSTRY CO., LTD)
(4) 1,4-butanediol (manufactured by Mitsubishi Chemical
Corporation)
(5) Trimethylolpropane (manufactured by MITSUBISHI GAS CHEMICAL
COMPANY, INC)
(6) N,N-dimethylaminohexanol (KAOLIZER No. 25 (trade name)
manufactured by KAO CORPORATION)
(7) N,N,N'-trimethyl-2-hydroxyethylpropylenediamine (POLYCAT17
(trade name) manufactured by Air Products and Chemicals, Inc.)
Example 1
Preparation of a Thermosetting Polyurethane Raw Material
Composition
27.6 parts by mass of the above-mentioned 4,4'-diphenylmethane
diisocyanate (1) and 57.6 parts by mass of polybutylene adipate (2)
(number average molecular weight: 2,000) were reacted at 80.degree.
C. for 120 minutes in a nitrogen atmosphere, thereby obtaining a
prepolymer. Moreover, 2.1 parts by mass of 1,4-butanediol (4), 1.7
parts by mass of trimethylolpropane (5), 11.8 parts by mass of
polyhexylene adipate (3) (number average molecular weight: 1,000),
and a catalyst shown in Table 1 were mixed, thereby obtaining a
curing agent.
(Production of a Cleaning Blade)
A sheet steel holder was prepared beforehand as a support member. A
phenol resin adhesive was applied to one end face of the holder.
The holder is placed in a cleaning blade molding die formed of an
upper die and a lower die in a state that the one end portion to
which the adhesive has been applied is projected into a cavity.
Next, a thermosetting polyurethane raw material composition
prepared by mixing the prepolymer and the curing agent was injected
into the cavity. Then, the raw material composition was allowed to
react and cured by heating at 130.degree. C. Subsequently, the
cured material was released from the die, and cut into a given
size, thereby producing a cleaning blade in which the blade member
was formed on the holder.
(Quantitative Determination of Nitrogen-Containing Compound)
The cleaning blade was immersed in methanol, and extraction was
performed for four days in an environment of 25.degree. C.
Subsequently, the cleaning blade was taken out, and then the
methanol used for the extraction was condensed using a rotary
evaporator, thereby obtaining a concentrate. Next, the methanol was
added to the concentrate using a measuring flask, thereby preparing
a given amount of a test sample. 1 .mu.L of the test sample was
analyzed by GC-MS. The detected nitrogen-containing compounds were
identified from the obtained mass spectrum, thereby calculating the
peak area of each nitrogen-containing compound.
In addition, each of the nitrogen-containing compounds detected in
the above analysis was separately prepared, thereby obtaining
methanol solutions whose concentrations were adjusted to be
different from each other. 1 .mu.L of each of the methanol
solutions thus obtained whose concentration was known was analyzed
by GC-MS, thereby preparing a calibration curve on the basis on the
resulting peak areas.
Based on the prepared calibration curve, the concentration of each
of the nitrogen-containing compounds contained in the test sample
was calculated, and then the total amount of the
nitrogen-containing compounds extracted from the cleaning blade was
calculated. Further, the total amount of elution of the
nitrogen-containing compounds per cm of the cleaning blade in its
longitudinal direction was calculated by dividing the total amount
of the extracted nitrogen-containing compounds by the length (cm)
of the cleaning blade in its longitudinal direction. The obtained
results are shown in Table 1.
The urethane elastomer formed as a blade member of the cleaning
blade was cut out, thereby obtaining a test sample. The test sample
was treated and analyzed in the same manner as in the cleaning
blade, thereby calculating the total amount of extracted
nitrogen-containing compounds. The total amount of the extracted
nitrogen-containing compounds was divided by the weight (g) of the
urethane elastomer test sample used for extraction, to thereby
calculate the total amount of elution of the nitrogen-containing
compound per g of urethane elastomer. The obtained results are
shown in Table 1.
N,N-dimethylaminohexanol was extracted as the nitrogen-containing
compound.
(Image Evaluation)
The obtained cleaning blade was installed in a toner cartridge
(laser beam printer LBP-5300, manufactured by Canon Inc.). This
laser beam printer was left standing for 30 days in an environment
of 50.degree. C./95% RH, and thereafter, an image was formed in an
environment of 15.degree. C./30% RH. The image thus formed was
visually observed, and then was evaluated according to the
following criteria:
A: no abnormalities were observed in the obtained image;
B: a slightly whitened portion was observed in the obtained image,
and the slightly whitened portion corresponded to the position in
contact with the cleaning blade of a drum or the position facing
the cleaning blade of a charging roller; and
C: a clear white streak was observed in the obtained image, and the
white streak portion corresponded to the position in contact with
the cleaning blade of a drum or the position facing the cleaning
blade of a charging roller.
Example 2
A cleaning blade was produced in the same manner as in Example 1
except that the catalyst was used in a proportion shown in Table 1.
Then, the amount of the extracted nitrogen-containing compound was
calculated, and the image evaluation was performed in the same
manner as in Example 1. The obtained results are shown in Table
1.
Moreover, N,N-dimethylaminohexanol was extracted as the
nitrogen-containing compound.
Example 3
A cleaning blade was produced in the same manner as in Example 1
except that a catalyst shown in Table 1 was used in a proportion
shown in Table 1. Then, the amount of the extracted
nitrogen-containing compound was calculated, and the image
evaluation was performed in the same manner as in Example 1. The
obtained results are shown in Table 1.
Moreover, N,N,N'-trimethyl-2-hydroxyethyl propylenediamine was
extracted as the nitrogen-containing compound.
Example 4
A cleaning blade was produced in the same manner as in Example 1
except that a catalyst shown in Table 1 was used in a proportion
shown in Table 1. Then, the amount of the extracted
nitrogen-containing compound was calculated, and the image
evaluation was performed in the same manner as in Example 1. The
obtained results are shown in Table 1.
Moreover, N,N,N'-trimethyl-2-hydroxyethyl propylenediamine was
extracted as the nitrogen-containing compound.
Comparative Example 1
A cleaning blade was produced in the same manner as in Example 1
except that a catalyst shown in Table 2 was used in a proportion
shown in Table 2. Then, the amount of the extracted
nitrogen-containing compound was calculated, and the image
evaluation was performed in the same manner as in Example 1. The
obtained results are shown in Table 2.
Moreover, N,N,N'-trimethyl-2-hydroxyethyl propylenediamine was
extracted as the nitrogen-containing compound.
Comparative Example 2
A cleaning blade was produced in the same manner as in Example 1
except that a catalyst shown in Table 2 was used in a proportion
shown in Table 2. Then, the amount of the extracted
nitrogen-containing compound was calculated, and the image
evaluation was performed in the same manner as in Example 1. The
obtained results are shown in Table 2.
Moreover, N,N,N'-trimethyl-2-hydroxyethyl propylenediamine was
extracted as the nitrogen-containing compound.
TABLE-US-00002 TABLE 1 Example 1 Example 2 Example 3 Example 4
Catalyst type N,N- N,N- N,N,N'-trimethyl- N,N,N'-trimethyl-
dimethylamino- dimethylamino- 2-hydroxyethyl 2-hydroxyethyl hexanol
hexanol propylenediamine propylenediamine Catalyst amount 300 600
300 550 (ppm) Amount of elution 0.6 1.3 5.9 11.9 of nitrogen-
containing compound per cm of cleaning blade in the longitudinal
direction (.mu.g/cm) Amount of elution 2.6 5.7 25.7 50.0 of
nitrogen- containing compound per g of urethane elastomer (.mu.g/g)
Image evaluation A A A A
TABLE-US-00003 TABLE 2 Comparative Comparative Example 1 Example 2
Catalyst type N,N,N'-trimethyl- N,N,N'-trimethyl- 2-hydroxyethyl
2-hydroxyethyl propylenediamine propylenediamine Catalyst amount
(ppm) 600 800 Amount of elution of 12.7 16.8 nitrogen-containing
compound per cm of cleaning blade in the longitudinal direction
(.mu.g/cm) Amount of elution of 55.7 73.7 nitrogen-containing
compound per g of urethane elastomer (.mu.g/g) Image evaluation B
C
As is clear from the results shown in Table 1, the cleaning blades
produced in Examples 1 to 4 caused no image defect resulting from
the contamination of the photosensitive drum and the charging
roller. In contrast, the cleaning blades produced in Comparative
Examples 1 and 2 causes an image defect. This is probably caused by
the nitrogen-containing compound vaporized from the cleaning blade
by moisture or heat.
While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is
not limited to the disclosed exemplary embodiments. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all such modifications and equivalent structures
and functions.
This application claims the benefit of Japanese Patent Application
No. 2007-109126, filed Apr. 18, 2007, which is hereby incorporated
by reference herein in its entirety.
* * * * *